The present invention relates to a retention mechanism, and particularly to a retention mechanism for securing edge cards in a range of different heights.
U.S. Pat. Nos. 4,507,707; 4,869,680; and 5,822,193 each disclose a retention mechanism for securing an edge card onto a printed circuit board. However, a disadvantage of the retention mechanism of the U.S. Pat. No. 4,507,707 is that the movable post 80 thereof only abuts an upper edge of the edge card 14, so the securing relationship therebetween is not firm. The assembly of the retention mechanism of the U.S. Pat. No. 4,869,680 requires pressing a plurality of spring-biased balls into corresponding holes, making it relatively difficult to assemble. A disadvantage of the retention mechanism of the U.S. Pat. No. 5,822,193 is that the assembly of the retention mechanism is more difficult because of its complicated structure. Other U.S. Pat. Nos. 3,829,741, 5,494,451 and 5,943,218 also show some card retention devices for use with the card.
An attempt is proposed to use a bolt positioned beside the card, wherein the bolt has a movable arm with a clamp capable of moving upwardly and downwardly along the bolt and capable of clamping the upper edge of the card. However, a disadvantage of this retention mechanism is that manufacturing the screw threads increases the difficulty and the cost of manufacturing the mechanism, and possibly tends to be reversely rotated and loosened under severe vibration. Moreover, rotating the movable arm along the threads of the bolt during assembling or disassembling the card, takes labor and time.
Thus, a retention mechanism with a relatively simple structure and an efficient and reliable securing device is needed to facilitate the assembly process, reduce the cost of manufacturing and guarantee the locking effect.